The answer is C) Alveoli.

Alveoli are small, balloon-like structures that are the site of gas exchange in the lungs. They are lined with blood vessels, and oxygen from inhaled air diffuses into the blood, while carbon dioxide from the blood diffuses into the alveoli to be exhaled.

• Trachea: The trachea, also known as the windpipe, is a large airway that carries air from the mouth or nose to the lungs.
• Bronchi: The bronchi are two large airways that branch off the trachea and lead to the right and left lungs.
• Alveoli: Alveoli are small, balloon-like structures that are the site of gas exchange in the lungs. They are lined with blood vessels, and oxygen from inhaled air diffuses into the blood, while carbon dioxide from the blood diffuses into the alveoli to be exhaled.
• Larynx: The larynx, commonly referred to as the voice box, is located at the top of the trachea and helps to control breathing and protect the airways.

The correct answer is C) Alveoli.